Site GUATB-03A
Priority:
2 (Alternate site)
Position:
6°40.64'N, 91°55.94'W
Water depth (m):
3621
Sediment thickness (m):
240
Target drilling depth (mbsf):
350–600
Approved maximum penetration (mbsf):
Approved for unlimited penetration according to ODP Leg 206 Scientific Prospectus; same approval requested for IODP Expeditions 309 and 312
Survey coverage:
Acquired during Ewing cruise EW9903, March–April, 1999:
• MCS with 480 channels, 10 air guns
• Refraction shooting 20 air guns recorded on OBHs
• 3.5 kHz reflection
• Hydrosweep multibeam bathymetry
Site GUATB-03A is on EW9903 Line 21 between Lines 26 and 27 (see Figure F10)
Objective:
• Establish regional variation in upper crustal processes, lithologic structure, and seawater interactions
• Determine the extent of the massive lava flow encountered in Holes 1256C and 1256D to constrain the size of off-axis eruptions and drilling further afield in the GUATB-03 survey region
Drilling and logging program:
• Single bit to destruction or free-fall funnel deployment for an additional bit trip if recovery warrants
• Because the sediment cover in the area has been documented in multiple cores, we request the option to wash through the sediment column a begin coring at the sediment/basement interface
Logging program:
• Triple combo
• FMS-sonic
• BGR borehole magnetometer: oriented magnetic field measurements
• UBI: acoustic borehole images
Nature of rock anticipated:
Pelagic sediment overlying basalt